The present invention relates generally to a method of manufacturing fibers with optical function in accordance with a melt spinning method and more particularly, to a method of manufacturing fibers with optical function, which reflect ultraviolet (UV) or infrared (IR) ray or show colors by reflection, interference, diffraction, or scattering phenomena of visible light ray.
Conventionally, a method of adopting inorganic or organic dyes and pigments or scaterring bright members has been in general use for providing various fibers and car coatings with desired colors or improved visual quality.
Recently, with an user's tendency to a high fabric quality, etc., there are increasing demands on graceful and quality minute structures which have colors varying with a change in the angle of view and having high chromas.
Some minute structures are developed and proposed to satisfy the above demands. One is a material showing a color by reflection, interference, diffraction or scattering without using dyes and pigments. The other is a material showing a deeper and brighter color by combining the above optical action and the dyes and pigments.
JP 43-14185 and JP-A 1-139803 disclose coated-type composite fibers with iridescence which are made of two or more resins having different optical refractive indexes. A journal of the Textile Machinery Society of Japan (Vol. 42, No. 2, pp. 55-62, published in 1989 and Vol. 42, No. 10, pp. 60-68, published in 1989) describes laminated photo-controllable polymer films for showing colors by optical interference, wherein a film with anisotropic molecular orientation is interposed between two polarizing films.
JP-A 59-228042, JP-B2 60-24847, and U.S. Pat. No. 4,514,459 disclose fabrics with iridescence conceived, e.g. from a South American morpho-butterfly which is well-known by its bright color tone varying with a change in the angle of view.
JP-A 62-170510 discloses fibers which show interference colors due to recesses with a predetermined width formed on the surface of the fibers. This document describes that formed fibers are fast and permanent in color due to no use of dyes and pigments.
With the minute structures as disclosed in JP 43-14185 and JP-A 1-139803, it is difficult to form fine fibers and minute chips or pieces, and to control the dominant wavelength (so-called "peak wavelength") of reflecting visible light ray.
On the other hand, with the minute structures as disclosed in JP-A 59-228042, JP-B2 60-24847, U.S. Pat. No. 4,514,459, and JP-A 62-170510, it is difficult to obtain desired coloring effect due to indefinite dimension (thickness, length, and refractive index) of the minute structures, etc.
For solving such inconveniences, JP-A 6-017349 (=U.S. Pat. No. 5,407,738) proposes new minute structures for showing bright and permanent colors varying with a change in the angle of view by reflection and interference of visible light ray. In this document, fibers have a cross section with parallel fin portions and a center or core portion perpendicular thereto, the parallel fin portions serving to reflect ultraviolet or infrared ray, or show colors by reflection and interference of visible light ray.
However, with the minute structures as disclosed in JP-A 6-017349 (=U.S. Pat. No. 5,407,738), it is difficult to form, e.g. the parallel fin portions of the fibers very thinly with a slight error and a reduced manufacturing cost.
It is, therefore, an object of the present invention to provide a method of manufacturing fibers having a predetermined function of reflection and interference with accuracy and a reduced manufacturing cost.